From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.polymtl.ca (smtp.polymtl.ca [132.207.4.11]) by sourceware.org (Postfix) with ESMTPS id D435A3857C5E for ; Wed, 3 Feb 2021 15:30:11 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org D435A3857C5E Received: from simark.ca (simark.ca [158.69.221.121]) (authenticated bits=0) by smtp.polymtl.ca (8.14.7/8.14.7) with ESMTP id 113FToNc026207 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 3 Feb 2021 10:29:55 -0500 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp.polymtl.ca 113FToNc026207 Received: from [10.0.0.11] (192-222-157-6.qc.cable.ebox.net [192.222.157.6]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPSA id 249D31E939; Wed, 3 Feb 2021 10:29:50 -0500 (EST) Subject: Re: Get Different Result for the same core file with different versions of gdb. To: Andy Fan Cc: gdb@sourceware.org References: <86e716f4-8f2a-22df-efff-38fff1c7d408@polymtl.ca> From: Simon Marchi Message-ID: <1c724f8d-4c60-2967-cc69-0de5100c7af6@polymtl.ca> Date: Wed, 3 Feb 2021 10:29:49 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Poly-FromMTA: (simark.ca [158.69.221.121]) at Wed, 3 Feb 2021 15:29:50 +0000 X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, NICE_REPLY_A, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_PASS, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: gdb@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 03 Feb 2021 15:30:13 -0000 > Hi Simon: > Thanks for your reply! Actually I am debugging postgresql bug, however > I can't reproduce the core at last, so the simple answer for your question is > no, I can't provide the reproducer. I'm sorry about that. But if you want any > further analysis on the current core file, I can try my best. I don't know core file handling well enough to provide you with precise instructions to guide you. If I had that it front of me, I would probably check which address GDB is trying to read (if it's the same in both cases). I would inspect the LOAD program headers of the core file, see what's the content at that address. If I find that GDB indeed is not reading the right content, I would try to bridge the gap between where LOAD program headers from the core file are processed and where memory is read in GDB, to try to find where the chain is broken. The relevant code for that is probably in gdb/corelow.c. Simon